We are examining the synthesis, structure, and hopefully, the significance of maternal messenger RNA-protein complexes (mRNP) during oogenesis and embryogenesis of certain large moths. Ultracentrifugation, affinity chromatography, and electrophoresis are used to isolate, analyze, and characterize both the protein and the RNA moeity of stored mRNP. Among the specific topics addressed are the mechanisms of inhibition of translation in the prefertilization period and the activation of translation at fertilization. The function of the protein moeity in control of translation and other possible roles for these proteins are examined. We hope to relate the kinetics of activation of transcription, translation and possibly replication to specific events of embryogenesis. We are also exploring the possibility that the location of various macromolecules in the ooplasm may be significant in determining the specific course of embryo differentiation. Other methods employed include microinjection, autoradiography, and ultrastructure observations of oocytes and early developing embryos.